Conventional semiconductor fabrication techniques such as optical lithography or extreme ultraviolet (EUV) lithography utilize a mask to form a pattern on a semiconductor wafer. In optical lithography, a semiconductor wafer is loaded onto a chuck, and a photomask is placed over the surface of the semiconductor wafer, thereby allowing a pattern on the photomask to be projected by a lens onto the semiconductor wafer. However, as new semiconductor wafers are introduced to the chuck during continued fabrication, undesired particles can appear and accumulate on the surface of the chuck, which can result in deformations on the surface of a semiconductor wafer placed on the chuck. These deformations can cause the pattern from the photomask to be out of focus on portions of the wafer and be inaccurately transferred onto the surface of the wafer, which can cause one or more dies on the wafer to become defective, thereby reducing yield and increasing manufacturing costs.
EUV lithography uses shorter wavelengths of light than conventional optical lithography, which can result in smaller patterning and hence more advanced semiconductor devices. In EUV lithography, a patterned reflective mask can be mounted on a chuck, and ultraviolet light can reflect the pattern through an optical system and onto a semiconductor wafer. However, similar to conventional optical lithography, undesired particles can accumulate between the chuck and the reflective mask and can cause inaccurate patterns to be formed on the wafer. This can cause one or more dies on the wafer to be defective, thereby increasing manufacturing costs by reducing yield.
In an attempt to reduce the number of undesired particles on the chuck, the chuck can be polished or cleaned before mounting each new semiconductor wafer or reflective mask. However, polishing or cleaning can damage the chuck and can cause significant downtime in the fabrication process, which also increases manufacturing costs.